| Synthetic wheat crossing with common wheat can avoid the difficulties of cross incompatibility and high sterility of hybrid progeny when using secondary gene source of wheats directly. Because of chromosome homology, chromosomes of the hybrid progeny can pair and recombine like those of progeny between common wheats. Through this way, many valuable genes from tetraploid wheat and Aegilops tauschii can be easily transferred into common wheat. The genetic linkage of adverse genes can be broken through backcross with common wheat. Compared with common wheat, tetraploid wheat and Aegilops tauschii carry some valuable genes, but they have lots of undesirable characters and need to be improved. In this research, we investigate and analyze the agronomic characters of hybrid progeny from synthetic wheat RSP crossing with common wheat LC10. The results provide some useful information to use synthetic wheat for wheat breeding. The main results are as follows:1 As sowing time being postponed and temperature rising, earing period of the different sowing time of LC10 and RSP was gradually advanced, so their growth period was shortened, and yield-related traits was obviously decreased. The results showed that the most appropriate sowing time of LC10 and RSP and their hybrid progeny was from the end of October to early November.2 It was showed from the investigation of agronomic traits that progeny with good agronomic traits might be screened from hybridization between synthetic wheat and common wheat. In F2 population, the earing period was ranged from 120 to 145 days, Individual of plant height less than 90 cm was 20%. Variation range of tiller number per plant was larger among individuals. Tiller number of a large number percentage of the plants was more than parent LC10 whose tiller was low. Individuals of F2 were mainly long spike with spike length mainly ranging from 12 to 17 cm, which help to increase the number of grain per spike. Individual of plant spikelet distributed from 20 to 24 was 23.12 %, while individual of multiple spikelet ranged from 25 to 27 was 2.52% in particular. It was showed that the spikelet number of hybrid progeny can be significantly increased by crossing synthetic wheat with common wheat. Individual of 1000-grain weight higher than 45g was 35.18% with the weightiest individual of 65.50g. Grain number per spike from 40 to 70 was up to 47.23%. Individual of grain weight per spike more than 2.5g was 10.55 %. Individual of yield per plant more than 25g was 6.03%. Yield per plant of most individuals in F2 was more than their parents. In this study, eight materials were screened with better agronomic traits.3 It was showed from the correlation analysis of agronomic traits that earing period was significantly positively related to plant height, and extremely significant positive correlated with spike length and number of spikelet. Plant height was extremely significant positive correlated with tiller, number of spikelet, grain number, grain weight, yield per plant, spike length, rachis internodes length and glumes hardness. It was suggested that tiller was highly significant positive correlated among spike length, number of spikelet and yield per plant. Spike length and other traits were similar to the correlation between plant heights. Spike length was extremely positively related to rachis internodes length and number of spikelet per plant. It was implied that the spike length relied on both rachis internodes growth and the increasing of the spikelet number per plant. It was extremely significant positive correlated between number of spikelet and grain number per plant, indicating that increasing number of spikelet is an effective way to increase grain number. Between grain number per spike and grain weight per spike and yield per plant showed significant positive correlation; so was 1000-grain weight and grain weight per spike and yield per plant; grain weight per spike and yield per plant also reached an extremely significant positive correlation. In the breeding of hybrid progeny, we can increase production by enhancing the grain weight per spike or 1000-grain weight or both.4 Single-scale test and the joint-scale test on 1000-grain weight, grain weight per spike and yield per plant were used to estimate the genetic parameters in quantitative genetic analysis of agronomic trait. The three parameters of 1000-grain weight was respectively m=29.4208±4.68051, [d]= 10.5979±4.70307, [h]=11.7954±9.76571; grain weight per spike was m=1.5475±0.32253, [d]=0.8430±0.32139, [h]= 0.3866±0.69630; those of yield per plant was respectively m= 7.6184±3.54324, [d]=3.1500±3.52479, [h]= 3.5303±6.63513. X2 testing expectations of generation mean showed that 1000-grain weight, grain weight per spike and yield per plant are less than X20.05 (3) value. It was showed that the genetic of these three traits can be explained by additive dominance model, both dominant effects and additive effects affected on these three traits. 5 Through analyzing glume tenacity trait and genetic control of prematurity, the results showed that F2 glum hardness consistent with 1:3 segregation ratio, but not match the 3:13 segregation ratio. This indicates that glume hardness character control by only a single gene. Using 22 pairs of SSR primers on 2D chromosome to analysis parents, the result displayed that 7 pairs of primers (Xgwm102,Xgwm484,Xgwm157,Xgwm296,gdm5,wmc112,barcl68) have polymorphism, these 7 molecular markers have linkage with glume hardness gene and earliness gene on 2D chromosome. In this research, the contribution rate of located glume hardness gene (QTL2 and QTL3) is only 2%, maybe it was false positive marker. The QTL1 of prematurity character linkage was located on 2D chromosome, and the statistic genetic distance between barc168 and earliness gene was calculated to be 0.4cM, contribution rate was 73%. But this site on 2D chromosome is whether photoperiod gene (Ppd-D1) or earliness pe se gene (Eps-2D) still need to be confirmed in future.
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